Feller bunchers having felling heads for cutting and accumulating cut trees are well known in forestry operations. Most of them are front cut heads with the head mounted on either the front of a drive to tree vehicle or on the front of a vehicle mounted boom in the case of a boom to tree machine. There have been two basic approaches to accumulating arm geometries in such machines in the past. One approach is dual symmetric arms. These would accumulate the first tree in the middle of the head. These provide good control and power, are suitable for larger trees, and can be used to pick up trees off of the ground, but limit the space available in front of the arms to cut subsequent trees as the head is fed forwardly through the tree during the cutting operation. More recently, single accumulator arm designs have been used, particularly for felling heads that are designed to accumulate larger numbers of smaller trees. The single arm permits the trees to be accumulated off of the center of the head, and thus permits more variety in the shape of the accumulating area, and generally larger accumulation areas. The single arm is not as effective in controlling one or two very large trees, however, and cannot be used for picking up cut trees off of the ground.